Low-voltage lamps distributed in the market presently, such as quartz halogen-tungsten lamps, have the properties of projecting in close quarters and being used safely etc., for theirs high color rendering index, they have been used extensively in commerce and domesticity. But it's necessary to use a voltage reducing transformer to supply power for the normal operation of the lamps, and to switch town electricity into an isolated and safe low voltage electricity. At present, for the voltage switch isolating transformer in this kind of electronic transformers, primary and secondary windings are normally winded on a magnetic core, and after insulation they are installed in the outer case of the electronic transformers. The outer case will isolate the voltage switch isolating transformer from environment completely. If it is desired to reduce furthermore the thickness of the electronic transformer with such a structure, the key problem is to reduce the height of the voltage switch isolating transformer. It is also a problem hardly to be broken through. For it is a magnetoelectricity apparatus of power, only reduces the thickness of materials, the safety and the reliability of the apparatus will not meet the requirement, and only reduces the thickness of the magnetic core, the magnetic property and the mechanical intensity of the magnetic core will deteriorate quickly, even to the extent that the apparatus can not be operated normally. At the present market, when the low voltage quartz halogen-tungsten lamp is used in the furniture such as cupboard, it is desirable that the electronic transformer installed coordinately can be a super-thin one. The space occupied by the transformer can not be too large and too high and the heat dispersion should be good enough so as to it can be used conveniently. Furthermore, to meet the particular requirements of the different installation space and structure, it is desired to be a lighter, thinner and more beautiful one.